Engine Replacement

[PD_400]

I recently bought a 1999 Mk2 1.6 MX5 which I've been advised needs a replacement engine due to a rattling noise around 2k revs.
I've been looking for a replacement unit and can find plenty of Mk1 engines but not many Mk2 engines and the ones I have found have been a lot more expensive. Does anyone know if the Mk1 engine will go into the Mk2 or is there something obvious I'm missing?

[GravelBen]

Apologies if you've already looked into this, but I'd be investigating much more thoroughly before replacing an engine based on a rattling noise!

[MX-5 Lazza]

I said similar in my reply on PlanetMX5.

[PD_400]

They've checked for all the obvious things but the rattles definatley coming from the engine block at 3k revs, not 2k, I'm typing this on my phone!